Under zero magnetic field, a quadrupolar order parameter at q Q = ( 1 2 , 1 2 , 1 2 ) in a typical antiferro-quadrupole (AFQ) ordering compound CeB 6 has been observed for the first time by means of a resonant X-ray scattering (RXS) technique. The RXS is observed at the 2p → 5d dipole transition energy of the Ce L 3 -edge. Using this RXS technique to observe the pure order parameter of the AFQ state, the magnetic phase diagram of Phase II is first determined.

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Based on experimental 59 Co-NMR data in the temperature range between 0.1 and 300 K, we address the problem of the character of the Co 3d-electron based magnetism in Na0.7CoO2. Temperature dependent 59 Co-NMR spectra reveal different Co environments below 300 K and their differentiation increases with decreasing temperature. We show that the 23 Na-and 59 Co-NMR data may consistently be interpreted by assuming that below room temperature the Co 3d-electrons are itinerant. Their magnetic interaction appears to favor an antiferromagnetic coupling, and we identify a substantial orbital contribution χ orb to the d−electron susceptibility. At low temperatures χ orb seems to acquire some temperature dependence, suggesting an increasing influence of spin-orbit coupling. The temperature dependence of the spin-lattice relaxation rate T −1 1 (T ) confirms significant variations in the dynamics of this electronic subsystem between 200 and 300K, as previously suggested. Below 200 K, Na0.7CoO2 may be viewed as a weak antiferromagnet with TN below 1 K but this scenario still leaves a number of open questions.

We report the results of 87 Rb NMR measurements on RbOs 2 O 6 , a member of the family of the superconducting pyrochlore-type oxides with a critical temperature T c = 6.4 K. In the normal state, the nuclear spinlattice relaxation time T 1 obeys the Korringa-type relation T 1 T = const and the Knight shift is independent of temperature, indicating the absence of strong magnetic correlations. In the superconducting state, T 1 −1 ͑T͒ exhibits a tiny coherence enhancement just below T c , and decreases exponentially with further decreasing temperatures. The value of the corresponding energy gap is close to that predicted by the conventional weakcoupling BCS theory. Our results indicate that RbOs 2 O 6 is a conventional s-wave-type superconductor.